1. Field of the Invention
Methods and apparatus consistent with the present invention relate to Universal Plug and Play (UPnP), and more particularly, to a method and apparatus for rapidly connecting a network disconnected due to an Internet Protocol (IP) address change of a UPnP device.
2. Description of the Related Art
Since a personal computer (PC) can automatically recognize peripherals using a Plug and Play function, a user can easily install peripherals. Universal Plug and Play (UPnP) is a technique of extending the Plug and Play function all over a network and allows devices (PCs, peripherals, home appliances, etc.) to automatically recognize each other when they are connected to the network.
FIG. 1 is a block diagram of a related art UPnP network apparatus. Referring to FIG. 1, the related art UPnP network apparatus includes a control point 11 and UPnP devices 12 and 13. In particular, the UPnP devices 12 and 13 may be a media server and a media renderer, respectively.
The control point 11 recognizes UPnP devices existing in a network and controls the recognized UPnP devices. The media server 12 provides UPnP content. The media server 12 may be a PC that provides media content. The media renderer 13 renders the UPnP content provided by the media server 12 according to a UPnP standard. The media renderer 13 may be a digital TV that reproduces media content.
FIG. 2 is a diagram for illustrating transmission of a UPnP alive message in a related art UPnP network apparatus. When a device is added to a UPnP network, the device transmits a UPnP alive message in a format, shown in FIG. 2, to a control point 11. In detail, FIG. 2 illustrates a case where a media server 12 is added to the UPnP network.
FIG. 3 is a diagram for illustrating transmission of a UPnP byebye message in a related art UPnP network apparatus. When a device is removed from a UPnP network, the device transmits a UPnP byebye message in a format, shown in FIG. 3, to a control point 11. In detail, FIG. 3 illustrates a case where a media server 12 is removed from the UPnP network.
Meanwhile, since the UPnP network apparatus is based on a TCP/IP (Transmission Control Protocol/Internet Protocol), a UPnP device in the network must have its own IP address. Thus, for the IP address, the UPnP device includes a Dynamic Host Configuration Protocol (DHCP) client module and an automatic IP module. When a DHCP server is not detected in a network in which the UPnP device is located, the automatic IP module generates an IP address and sets it as an IP address of the UPnP device. When a DHCP server is detected in the network in which the UPnP device is located, the DHCP client module requests the DHCP server to provide an IP address, obtains the IP address as per the request, and sets it as an IP address of the UPnP device.
However, sometimes an IP address of a UPnP device is changed while the UPnP device is connected to a UPnP network based on the IP address. For instance, when a lease period of an IP address of a UPnP device, which is prescribed by the DHCP server, expires and the DHCP server allocates another IP address to the UPnP device, or when the DHCP server does not normally operate, and thus, the automatic IP module generates another IP address.
When the IP address of the UPnP device is changed, a network connection based on the IP address is disconnected, and a new network connection is established based on the changed IP address. Therefore, the UPnP device transmits the byebye message illustrated in FIG. 3 to the control point 11 and then transmits an alive message, shown in FIG. 2, to the control point 11.
The change in the IP address of the UPnP device changes a uniform resource locator (URL) via which a control request is transmitted to the UPnP device, i.e., via which a simple object access protocol (SOAP) request message is received; and a URL via which a request for an event is transmitted to the UPnP device, i.e., via which a general event notification architecture (GENA) request message is received. Also, all information, e.g., a state variable, regarding the UPnP device is removed from the control point 11, and new information regarding the UPnP device is generated based on the changed IP address.
Also, if the IP address of the UPnP device is changed, all of the sessions based on the previous IP address are discontinued, thereby stopping services irrespective of a user's intention. Thus, the user must restart the stopped services. If the IP address of the media server 12 or the media renderer 13 is changed to discontinue the content streaming session based on the previous IP address, the user experiences a pause in reproduction of content using the media renderer 13. In this case, the user must detect a point where content streaming is discontinued and restart content streaming at the detected point based on a new IP address.